Field of the Invention
This invention generally relates to power source switching to electrical loads, specifically portable transfer switches that select which power source to feed the electrical loads.
Background of the Invention
Automatic transfer switches exist to supply multiple power sources to a load. These devices ensure a supply of power should one of the power sources become unavailable.
The advantages of these types of systems are known but there are some disadvantages. Transfer switches are permanent fixtures where they are installed and establish permanent electrical connections to the power sources and to the loads.
Another disadvantage is that in many cases these transfer switches operate in the absence of logic, in an automatic manner. They will switch to a secondary power source based on the single condition that a primary power source becomes unavailable.
Furthermore, the operation of these automatic transfer switches doesn't account for equally viable power being available from more than two power sources. This means there will be no possibility to optimize many consumer based considerations including cost of power, and consumption of power from desired power sources. For example, if a user wants to have their electrical loads served by renewable energy as a primary source and only switch over to utility power when the solar power source is not available in order to save money on their power bill, a transfer switch that facilitates this option would be desirable.
In many cases, transfer switches select utility power as a main or primary source and only switch to generators or alternate power sources when utility power is interrupted. It is therefore desirable to have a way to power electrical loads from alternative sources such as solar, fuel cells or generators as a primary source, with the utility as secondary.